Only write a single MONTHLY rule when serializing to iCal format

[lukebooth]

I couldn't find the exact rule in the RFC 2445, but having multiple RRULE:FREQ=MONTHLY;... in an iCal file was confusing GCal and MS Outlook.

[boblail]

3.8.5.3: RRULE . . . SHOULD NOT be specified more than once.

🤔

But Hiccup allows a Schedule to recur:

• On the 10th day of every month and
• On the 3rd Thursday of every month

In this case, the iCal would see only the 3rd Thursday rule.

Should we alter Hiccup (and the UI of our products that use it) so that you can't mix-and-match monthly by-day and monthly by-weekday types?

[lukebooth]

I think we decided we would like the UI in all the apps to be able to generate recurrences that can be exported to iCal format — And that we'd do that sometime in the future. Do we want to table this (add archived) or just leave it be until we get back around to it?

[boblail]

Let's archive it.